Intracavity grating to suppress single order of ring resonator

Abstract

Microwave-to-optical transducers in an optical ring resonator having intracavity grating to split a single resonance order are provided. In one aspect, a microwave-to-optical transducer includes: an optical ring resonator with intracavity grating; and a microwave signal waveguide optically coupled to the optical ring resonator with the intracavity grating. Microwave-to-optical transducers having multiple pump photon optical ring resonators and multiple signal photon optical ring resonators optically coupled to the optical ring resonator with the intracavity grating are also provided, as is a method of forming a microwave-to-optical transducer, and a method for microwave-optical transduction.

What is claimed is: 
     
       1. A microwave-to-optical transducer, comprising:
 an optical ring resonator with an intracavity grating comprising a core and an evanescent feature adjacent to the core; 
 an input pump photon waveguide for carrying optical input photons towards the optical ring resonator with the intracavity grating; and 
 a microwave signal waveguide for carrying microwave input photons towards the optical ring resonator with the intracavity grating. 
 
     
     
       2. The microwave-to-optical transducer of  claim 1 , wherein the evanescent feature comprises:
 a base portion; and 
 a width modulation portion having a width that modulates continuously along a surface of the base portion facing the core to form the intracavity grating. 
 
     
     
       3. The microwave-to-optical transducer of  claim 2 , wherein the intracavity grating has a sawtooth pattern. 
     
     
       4. The microwave-to-optical transducer of  claim 2 , wherein the core and the evanescent feature are surrounded by a cladding material. 
     
     
       5. The microwave-to-optical transducer of  claim 4 , wherein the core and the evanescent feature comprise silicon germanium (SiGe), and wherein the cladding material comprises silicon (Si). 
     
     
       6. The microwave-to-optical transducer of  claim 1 , wherein the optical ring resonator with the intracavity grating and the microwave signal waveguide are formed on a substrate comprising a material selected from the group consisting of: sapphire, diamond, silicon carbide (SiC), gallium nitride (GaN), and combinations thereof. 
     
     
       7. The microwave-to-optical transducer of  claim 1 , further comprising:
 multiple pump photon optical ring resonators optically coupled to the optical ring resonator with the intracavity grating forming an isolated pump photon pathway; and 
 multiple signal photon optical ring resonators optically coupled to the optical ring resonator with the intracavity grating forming an isolated signal photon pathway. 
 
     
     
       8. The microwave-to-optical transducer of  claim 7 , further comprising:
 an output pump photon waveguide; 
 a first pump photon optical ring resonator optically coupled to the input pump photon waveguide and to the optical ring resonator with the intracavity grating; and 
 a second pump photon optical ring resonator optically coupled to the output pump photon waveguide and to the optical ring resonator with the intracavity grating. 
 
     
     
       9. The microwave-to-optical transducer of  claim 7 , further comprising:
 an output signal photon waveguide; 
 a first signal photon optical ring resonator optically coupled to the optical ring resonator with the intracavity grating; 
 a second signal photon optical ring resonator optically coupled to the first signal photon optical ring resonator; and 
 a third signal photon optical ring resonator optically coupled to the second signal photon optical ring resonator and to the output signal photon waveguide. 
 
     
     
       10. A microwave-to-optical transducer, comprising:
 an optical ring resonator with an intracavity grating comprising a core, and an evanescent feature adjacent to the core; 
 an input pump photon waveguide for carrying optical input photons towards the optical ring resonator with the intracavity grating; 
 a microwave signal waveguide for carrying microwave input photons towards the optical ring resonator with the intracavity grating; 
 multiple pump photon optical ring resonators optically coupled to the optical ring resonator with the intracavity grating forming an isolated pump photon pathway; and 
 multiple signal photon optical ring resonators optically coupled to the optical ring resonator with the intracavity grating forming an isolated signal photon pathway. 
 
     
     
       11. The microwave-to-optical transducer of  claim 10 , wherein the evanescent feature comprises:
 a base portion; and 
 a width modulation portion having a width that modulates continuously along a surface of the base portion facing the core to form the intracavity grating. 
 
     
     
       12. The microwave-to-optical transducer of  claim 10 , wherein the core and the evanescent feature are surrounded by a cladding material. 
     
     
       13. The microwave-to-optical transducer of  claim 12 , wherein the core and the evanescent feature comprise SiGe, and wherein the cladding material comprises Si. 
     
     
       14. The microwave-to-optical transducer of  claim 10 , wherein the optical ring resonator with the intracavity grating, the microwave signal waveguide, the multiple pump photon optical ring resonators, and the multiple signal photon optical ring resonators are formed on a substrate comprising a material selected from the group consisting of: sapphire, diamond, SiC, GaN, and combinations thereof. 
     
     
       15. The microwave-to-optical transducer of  claim 10 , further comprising:
 an output pump photon waveguide; 
 a first pump photon optical ring resonator optically coupled to the input pump photon waveguide and to the optical ring resonator with the intracavity grating; and 
 a second pump photon optical ring resonator optically coupled to the output pump photon waveguide and to the optical ring resonator with the intracavity grating. 
 
     
     
       16. The microwave-to-optical transducer of  claim 10 , further comprising:
 an output signal photon waveguide; 
 a first signal photon optical ring resonator optically coupled to the optical ring resonator with the intracavity grating; 
 a second signal photon optical ring resonator optically coupled to the first signal photon optical ring resonator; and 
 a third signal photon optical ring resonator optically coupled to the second signal photon optical ring resonator and to the output signal photon waveguide.